As traveling assistance control of a vehicle, various types of control, such as an adaptive cruise control system and lane keeping assist, are known. In the adaptive cruise control system, a vehicle traveling in a same traffic lane as an own vehicle is selected as a leading vehicle, and the own vehicle travels such as to track the selected leading vehicle. In lane keeping assist, traveling of a vehicle is controlled such that the vehicle does not deviate from left and right traveling demarcation lines.
In such traveling assistance control, a camera is mounted to the vehicle. An image of an area ahead of the vehicle is captured and traveling demarcation lines are recognized. In addition, traveling of the vehicle is controlled through use of the recognized traveling demarcation lines (for example, refer to PTL 1). Regarding an apparatus described in PTL 1, it is disclosed that a clothoid parameter is calculated from traveling demarcation lines in an image captured by a camera. The clothoid parameter indicates a degree of curvature of a course. Future behavior of a vehicle on the course is predicted through use of the calculated clothoid parameter.